new Promise((resolve, reject) => {
    setTimeout(() => {
        let a = 'hello '
        resolve({ a });
    }, 100)
}).then((value) => {
    return new Promise((resolve, reject) => {
        setTimeout(() => {
            let b = 'lagou '
            resolve({ ...value, b: b });
        }, 100)
    })
}).then((value) => {
    return new Promise((resolve, reject) => {
        setTimeout(() => {
            let c = 'I ❤ U'
            resolve({ ...value, c: c });
        }, 100)
    })
}).then((value) => {
    const { a, b, c } = value;
    console.log(a + b + c)
})